1. Field of the Invention
The present invention relates to a multi-frequency millimeter-wave Very Long Baseline Interferometry (VLBI) receiving system and a method of designing a quasi optical circuit for the multi-frequency millimeter-wave VLBI receiving system, and more particularly, to a multi-frequency millimeter-wave VLBI receiving system for performing radio astronomic observations simultaneously in 22 GHz, 43 GHz, 86 GHz, and 129 GHz bands, and a method of designing a quasi optical circuit for the multi-frequency millimeter-wave VLBI receiving system.
2. Description of the Related Art
During past several years, many observations were conducted using millimeter-wave VLBI. However, phase fluctuations caused by the troposphere impose a limit on the imaging ability of the millimeter-wave VLBI and reduce the sensitivity of the millimeter-wave VLBI.
To implement compensation for the tropospheric phase fluctuation with the lowest frequency band, a special multi-frequency quasi-optical system pointing the same position in sky needs to be devised.